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REPORT 


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OF BOARD OF ENGINEERS 


—ON— 

fitly (Means Darbor, 

i 

APRIL 8th, 1878 


G. WE1TZEL, 

W. I1JL BENYAURD, 
C. W. HOWELL, 

B. M. HARROD. 

ROB’T 0. WOOD, Secretary. J. A. d’HEMECOURT. 



NEW ORLEANS: 

Seymour & Stevens, print, 96 Common St. 

1878 . 

- ' ' - . 










REPOET 


OF BOARD OF ENGINEERS 




—ON— 



(Means Sarkr 


APRIL. 8th, 1878. 


G. WEITZEL, 

W. H. H. BENYAURD, 
C. W. HOWELL, 

B. M. HARROD. 

ROB’T C. WOOD. Secretary. J. A. d’HEMECOURT. 



NEW ORLEANS: 

Seymour & Stevens, print, 96 Common St. 


1878 . 











REPORT. 


At the regular meeting of the City Council of New Orleans, 
ou October 16, 1877, Hon. Chas. Cavanac, Administrator of 
Commerce, presented the following resolution : 

Resolved , That the Mayor be and is hereby authorized and 
directed to cause an accurate survey and sounding ot the river 
to be made trom Morgan’s Landing to the lower limits of the 
Third District, in order to determine the character and location 
of channel, the velocity of current, the depth of water, the 
nature of the banks and such other data as will be necessary in 
effecting the permanent relief proposed. 

In compliance with this resolution, which was unanimously 
adopted, Hon. E. Pilsbury, Mayor, proceeded to the formation of 
a Board of Engineers. 

Invitations were extended to Geul. G. Weitzel, Major W. H. 
H. Benyaurd and Major C. W. Howell of the U. S. Corps of En¬ 
gineers, and to Mr. B. M. Harrod, Chief Engineer of the State 
of Louisiana, and with these gentlemen was associated Mr. J. 
A. d’Hemecourt, City Surveyor, 

The Board thus composed convened in New Orleans, ou the 
morning of November 17, 1877, aud after organizing, addressed 
the following communication to the Mayor: 

Board of Engineers, | 
New Orleans, La., Nov. 17th, 1877. J 

Hon. Ed. Pilsbury, Mayor City of New Orleans: 

Sir —The Board of Engineers convened to consider questions 
relating to protection of the City front, is now in session and 
would be pleased to receive from you a detailed statement of 
your views as to the duty required of them. 

It is desirable to have explicit instructions as to extent and 
character of the investigation you desire and as to points to be 
covered by report. 

Very respectfully, 

Your obedient servant, 

G. Weitzel. 


<o -/!??; 



4 


To this communication the following reply was received: 

State of Louisiana, 
Mayoralty of New Orleans, 
City Hall, Nov. 17th, 1877. 
Major General G. Weitzel, U. 8. Engineers: 

Sir —In reply to yours of even date, I have the honor to sub¬ 
mit the following points, which appear to me desirable in con¬ 
nection with your presence as a Board of IJ. S. Engineers. 

1st. A thorough and complete survey of the river and its 
banks from the upper to the lower limit of the City, giving cross 
sections of the stream every half mile, and the direction of the 
current. 

2d. A plan for the temporary preservation of the banks and 
wharves from destruction, to apply only to the most exposed 
points, and adapted to the present resources of the city, which 
are limited, accompanied by estimates. 

3d. A more general and comprehensive plan, embracing the 
river front of the Second and Third Districts, as a permanent 
work, with estimates, so as to be commenced and carried on 
gradually as the future prosperity of the City may admit. 

Your obedient servant, 

E. PlLSBURY, 

Mayor, 

Letters of invitation were then addressed to distinguished 
local Engineers and others, requesting them to meet the Board 
on the 19th iust., and give the members the benefit of their per¬ 
sonal experience and opinions. 

Four interrogatories were propounded, the responses to which, 
together with other matter, will be found in the appendix. 

The Board remained in session until the 23d inst, engaged in 
a thorough examination of the harbor, study of data, plans, etc. 
On this day the following preliminary report was rendered: 


New Orleans, Nov. 23, 1877. 

Hon. Ed. Pilsbury, Mayor: 

Sir —I have the honor of submitting a preliminary report of 
the Board of Engineers convened here by invitation of the City 
Government. 

Permission to accept the iuvitation on the part of Major 



5 


Benyaurd and myself was conditioned upon a uon-interfer- 
<ence with our duties as public officers. Our presence in our re¬ 
spective Districts at the end of this month is necessary. 

Full arrangements have been made for the continuance of the 
work during our absence, and the resident members of the 
Board have been directed to confer with your Honor in all mat¬ 
ters pertaining to it. 

Upon the completion of the Hydrographic Survey, which is 
essential to the objects we have in view, Major Benyaurd and I 
will return to New Orleans, iu order that final action and report 
of the Board may not be delayed. 

1 respectfully suggest that your Honor place at the service of 
the resident members of the Board competent and reliable 
divers to make such examinations as may be deemed necessary 
to the prosecution of their labors. 

Very Respectfully, 

Your Ob’t Servant, 

G. WE1TZEL. 

New Orleans, Nov. 23, 1878. 
Hon. Ed. Pilsbury, Mayor , City of New Orleans: 

Sir —The Board of Engineers convened at the request of the 
City Council “to examine and report upon the means necessary 
to protect the harbor of New Orleans, from the incursions of the 
river,” has the honor to submit the following preliminary report. 

While the Board has been able, from study of the data at its 
command, to decide upou the general features of a plan for the 
permanent protection of the whole City front and its wharves, 
it is thought advisable to await completion of the careful hydro- 
graphic survey called for by your Honor in your letter of in¬ 
struction of the 17th iust., before presenting a detailed plan and 
estimates for the protection of the whole front. 

We desire simply to present at this time our views as to what 
may be done at the most important points, aud outline a 
general [dan, the details of which, together with estimates, will 
be given in a report to be made after results of the survey for 
which you have provided may be made available. 

The Board has made a careful examination into the condition 
of affairs existing along the City front; has examined the valua¬ 
ble charts and reports placed at its disposal by the State and 


6 


City Engineers, and has obtained iu writing and conversation 
the opinions of distinguished local engineers and other gentle¬ 
men, whose professional or other interest in the questions pre¬ 
sented to the Board, has led them to pay attention to the mat¬ 
ter of river front protection. 

All this information will be submitted with our final report. 

The general plan of protection that in the opinion of the 
Board offers the most certain result, and besides appears the 
most economical, is one that for two centuries or more has been 
successfully followed for the protection of caving banks and 
abraded sea shores iu Europe, especially in Holland and Ger¬ 
many. It has been for many years also successfully applied by 
American engineers on the Northern lakes, in the Missouri river, 
and on the Mississippi river above Cairo. 

The method consists in the protection from scour by currents 
and eddies, of the unstable strata exposed in the sloping por¬ 
tions of the river bed, which by being washed out permits 
portions of the banks to drop down or slide into the river, thus 
\ frequently causing great loss of property. 

The method is that of revetment, and its details have de¬ 
pended in a large measure on the character of the material suit¬ 
able for the purpose and most easily and cheaply obtained and 
applied. 

Where there is an abundance of small growth timber, such as 
is found in great quantity in the swamps ol Louisiana, along 
the banks of the Mississippi and the higher portion of the river 
battures, this has been generally used, and in great variety of 
shapes of hurdles, mats, mattresses, fascines, rough bundles 
and even throwu in loose ballasted with natural or artificial 
stone, or secured to the caving slope by piliug or by stakes. 

A variety of other material that may be converted into the 
shapes above named has also been used, such as the longer, 
coarser grasses, reeds, straw, bagasse, etc. 

The Board is confident that this system of revetment judi¬ 
ciously applied all along the exposed portion of the City front 
may be made to effectually protect it, and at a reasonable ex¬ 
pense, but owing to changes that have occurred since the date 
of the latest survey available, the details of construction of re¬ 
vetment, which must be varied to suit the local peculiarities 
and the distance to which revetment must at points be carried 
from the shore line, can only be fully decided upon after the de- 


7 


tailed survey, for which you have provided, shall have been 
completed. As a consequence, estimate must also be postponed 
until that time. 

The Board has been presented with the most exact data as to 
the cost of various revetment works of the character suggested, 
and hope to be able soon to offer a close estimate for that rec¬ 
ommended in this case. 

In the meantime, however, there are two points along the 
City front at which works designed for protection are now in 
progress, which seem to call for the immediate action of the 
Board. 

The cave iu the 3d District, opposite the Atlantic Cotton 
Press, is one of the points. At this place the river has en¬ 
croached upon the laud so that at this time the shore line is 
found where it was 35 or 40 years ago, having washed away 
about one hundred (100) feet of ground formed by it in front of 
the levee since that time. 

It is possible that this cave has reached its limit, as it did 
then. The shore line may again begiu to build out into the 
river; but as a wise measure of precaution, it is deemed advis¬ 
able to continue the work of protection now in progress under 
the direction of the City Surveyor, with modification to meet the 
general views of the Board. 

It is evident that the defective strata, from which there is 
the most trouble to be apprehended, lie between the shore line 
and the front line of the wharves. 

It is therefore recommended that the single line timber 
bulkhead be completed, and the slope in front carpeted with 
hurdles or fascine mats or bundles of brush made into rafts aud 
sunk upon the bottom with ballast stone for a sufficient distance 
out to cover these strata and protect them from further scour. 

The Board does not wish to hamper the engineer in charge 
by specifying details, since in the cpurse of construction his fre¬ 
quent soundings may indicate cause for change iu minor details. 
He has been requested to submit a project for the work under 
the general plan suggested, aud with it present estimates. 

The cave at the head of Soraparu street is but a short one, 
occupying the space between two wharves. 

From the report of Mr. M. W. Francis, the diver who exam¬ 
ined the slope at this point, it appears that the defective 


8 


stratum lies at a depth of 25 feet, and that it is from 10 to 15 
feet in thickness, its upper edge slightly overhanging. At a 
depth of about 70 feet, which lies outside the line of wharf front, 
he found a very stable stratum. 

At this point the same measures are recommended as at the 
cave in the 3d District; the hurdle mat or fascine revetment to 
extend from the bulkhead out to the depth of 70 feet, unless 
examination should indicate it, may not be necessary to revet 
so far out. 

The City Surveyor has been requested to also submit project 
and estimate for this work. 

The resident members of the Board have been requested to 
confer with your Honor as to direction, character and extent of 
survey, and in every way represent the Board during its recess. 

All of which is respectfully submitted. 

G. Weitzel, 

W. H. H. Benyaurd, 

C. W. Howell, 

B. M. Harrod, 

J. A. d’Hemecourt. 

Robt. C. Wood, Secretary. 

General Weitzel and Major Benyaurd being compelled to ie- 
turn to their respective stations, the three resident members of 
the Board were charged with the supervision and execution of 
the work of survey, etc., necessary to the final plans and report 
of the Board. 

From November 23d, 1877, to April 2d, 1878, when the full 
Board reconvened, the various works of survey, sounding, etc., 
were vigorously prosecuted under the immediate charge of En¬ 
gineers selected for that purpose. 

From April 2d to April 8th, the Board was engaged in the 
examination of maps, plans, charts, etc., and on the latter day 
presented the following report. 


New Orleans, April 8, 1878. 
Hon. Ed. Pilsbury, Mayor of New Orleans: 

Sir —The Board of Engineers, convened at the request of the 
City Council “to examine and report upon the meaus necessary 
to protect the wharves and harbor from the incursions of the 
river, 77 beg to submit the following: 


9 


Referring to your letter of November 17, 1877, the engineer¬ 
ing information requested of the Board was as follows : 

1. A thorough aud complete survey of the river and its bank 
from the upper to the lower limit of the city, giving cross sec¬ 
tions of the stream every half mile and the direction of the 
current. 

2. A plan for the temporary preservation of the banks and 
wharves from destruction—to apply only to the most exposed 
points, and adapted to the present resources of the city—which 
are limited, accompanied by estimates. 

3. A more general aud comprehensive plan, embracing the 
river front of the Second and Third Districts, as a permanent 
work, with estimates, so as to be commenced and carried on 
gradually, as the future prosperity of the city may admit. 

At a former session of the board, held in November last, a pre¬ 
liminary report was rendered your Honor, respecting the con¬ 
dition of affairs along the city front. In this the means necessary 
to be taken to preserve the most exposed poiuts (which were at 
the foot of Sorapuru street, and at the foot of Montegut street,) 
were presented, aud the execution of the plans were entrusted 
to and carried out under the direction of the City Surveyor. A 
general plan also was outlined, which was to embrace the entire 
city from Carrollton to a point below the United States Barracks, 
or so much of it at least as needed permanent protection. The 
board was unprepared at that time to decide upon all the details 
to be observed in this permanent plan of protection, owing to 
the lack of the necessary information respecting the condition of 
the caving banks, their extent, their composition, slope, depth of 
water, etc., all of which could only be furnished by an exhaustive 
and extensive survey such as called for by your letter. 

This survey was undertaken under the personal supervision 
of the local members of the board, with aid furnished by the 
government and by the city, and was carried to a successful 
termination. It is complete and thorough in all the details 
necessary for a proper study of the problem submitted to the 
board. It extended from a point above Carrollton to a point 
below the Barracks, embracing also the right bank of the river, 
and was made in three sections. 

Section 1 started from a point some 3300 feet above the 
Metairie road, at the upper end of a plank revetment, where 


10 


there is a wide batture, and followed the left bank to the Orleans 
Park, where there is also a wide batture, a total distauce of 
22,243 feet. At intervals of 100 feet lines of soundings were 
made, extending out from 300 to 400 feet, and where there were 
caviug banks intermediate lines were sounded. Thirty-four 
sections were also sounded across the river iu this stretch, and 
from 100 to 120 soundings were located on each section. Thirt}’ 
of these cross sections were nearly at the same points as those 
made in the survey of 1851 by Capt. (now General) Humphreys. 

From the Orleans Park to Canal street, there being no caving 
of the left bank, no survey of that line was made. 

Section 2 commenced at Canal street, and the shore line was 
run from that point to the Slaughter-House, a distance of 21,800 
feet. On this stretch soundings were made at each 100 feet as 
before, extending out into the river from 300 to 400 feet. 
Twenty cross sections were also sounded at nearly equal inter¬ 
vals, but only about eighty souudiugs were located on each one. 

Section 3 included the right bank of the river, and com¬ 
menced at a point 3450 feet above the lock at Westwego, and 
extended down to the point at Algiers, and is some 47,000 feet 
in length. Soundings were made at intervals as in the surveys 
of the other sections, and 19 cross sections were sounded across 
the river between the lower eud of the Carrollton section and 
Canal street, thus filling that interval. 

Gauges were kept at Carrollton, Canal street, the Mint, and 
at the United States Barracks, and all soundings were reduced 
to the same plane of reference as that of the Delta survey, and 
reads on the Carrollton gauge, 15.70. 

The condition of the banks as developed by the survey, is as 
follows: From the upper end of the Carrollton survey to station 
186, there is a wide batture and no caving going on at present; 
from station 186 to station 91 (at head of Carrollton Avenue), 
there is more or less caving of the bank throughout the whole 
distance. Between stations 140 and 157 some 500 feet of the 
bank have caved in since 1858, and at the Carrollton Hotel, 
which is at the lower end of the present cutting, in that time 
some 200 feet have gone iu. The total length of the caving in 
this section is 9200 feet. 

From station 91 down to station 55 there have been about 
200 feet caved in since 1858, but there is little, if any, caving 


11 


going on now, except in two places—one about 300 and the 
other about 200 feet long. Below station 55, there is a fill at 
present and a wide batture. 

Below Canal street from Morgan’s wharf, at station 10 to sta¬ 
tion 160, a distance of 15,000 feet, the bank needs more or less 
protection. It has, however, only been deemed advisable to 
apply protective measures to the slope of the bank from Mor¬ 
gan’s wharf to Congress street, a distance of 7500 feet, leaving 
the remaining portion of the city below that point to be pro¬ 
tected by a new levee. 

On the right bank the space through which the caving takes 
place extends from station 49 to 176, below the locks, and from 
station 296 to 476 above and at Algiers, a total length of 31,700 
feet. The board, however, does not deem it at present abso¬ 
lutely necessary to apply the works of protection to this entire 
stretch of bank, but only to a portion embracing Nine-Mile 
Point. The locations of the different caving banks at which it 
is proposed to apply the works of protection can better be un¬ 
derstood by reference to the sketch map accompanying the 
report, while at the same time an inspection of the index and 
detailed maps will give all the information respecting the depths 
of water, slope of bank, composition of same, etc., much more 
fully than can be indicated or enumerated in the report. 

The results of the survey of the banks show that they are 
composed of a hard blue mud, with intermediate soft strata. 
These soft strata outcrop at varying depths, as shown on adja¬ 
cent lines ol soundings. In some cases they are quite regular, 
in others quite irregular, as if deposited upon a slope. The cav¬ 
ings result from the saturation of these layers of soft material, 
which are afterwards washed or cut out, causing the superin¬ 
cumbent mass to fall or slide into the river. This caving takes 
place mostly upon a falling river, the high water seeming to act 
by its pressure in sustaining the bank. These soft strata occur 
at various depths from near the surface to near the bottom of 
the river, and the greater or lesser amount of cave seems to de¬ 
pend upon their relative position. 

In order, then, to retain the bank in its natural position, the 
remedy to be applied would seem to be some method by which 
the cutting out of the defective strata could be prevented. This 
is best subserved by applying to the bank a revetment extend- 



12 


ing so as to cover the whole slope, or so much of it as is likely 
to be affected. The banks along the city front present condi¬ 
tions not unfavorable to the successful application of a project, 
such as was outlined in our preliminary report of November 
last. The general method indicated there was to cover the 
slope of the bank with a revetment of brush and stone in such 
shapes and forms as best suited the particular locality where it 
was to be applied. 

While much more costly applications of timber and stone 
might subserve the object in view, those of brush and stone in 
the shape of matting applied to the banks have the merit, that 
while suitable for the purpose, they are comparatively cheap, 
are durable, are easily applied, and on accouut of their pliabil¬ 
ity can be well adapted to the irregular slopes of the banks 
caused by the caving. At the same time the carpeting of the 
bank in such a manner causes no undue contraction of the water 
way, and allows the current to move along in its natural course. 

At the upper section of the river at Carrollton, and on the 
right bank above Algiers, where there are no wharves, it is pro 
posed, in accordance with the above views, to cover the slopes 
from a short distance above low water to a distance out such 
that all defective strata will be protected by a layer of brush 
formed into rafts and ballasted with stone sufficient to keep 
them in position. 

Along the section of the river from Morgan’s wharf to the 
foot of Congress street, it is proposed to form a bulkhead ex¬ 
tending the entire distance in a line with the outer row of wharf 
piles, by driving piles in pairs, the distance between the centres 
of each pair being six feet, and between the piles of each pair 
three feet. These piles are bolted together at low water and at 
the top. Between the piles and extending up and down stream, 
brush facines are piled up to low water mark, forming, so to 
speak, a brush wall. Above low water mark on the outside of the 
piles, plank are placed extending to high water mark. From 
the foot of this row of piles, extending out as far as may be ne¬ 
cessary, to cover all defective strata, a layer of brush and stone 
in suitable form is laid upon the slope. The object in not con¬ 
tinuing the revetment clear up to the banks, as in the other 
districts, is that it has been found from experience that great 
difficulty and expense will attend the removal of the great num- 


13 


ber of piles and timber work now forming the wharves and oc¬ 
cupying a portion of the slope needing protection, and which it 
would be necessary to remove were it determined to carpet the 
entire slope, adding considerably to the expense and more than 
circumstances would warrant. 

Statistics at the disposal of the Board indicate that the 
largest interests involved are in section 2, from Morgan’s wharf 
to Congress street. It therefore seems expedient that the pro¬ 
posed measures of protection should first be applied to that part 
of the shore. Similar reasons indicate that the work on the 
Carrollton section, No. 1, should be next done, and, finally, that 
work above the Nine-Mile Point, on the right bank, which is es¬ 
sential as a protection to works in section 1 and the shore 
below. 

The following are the estimates for the protection of so much of 
the city front as the Board deems absolutely essential at the 
present time to the preservation ot the wharves and harbor, 
though eventually the protection of the entire trout may have to 
be undertaken. These estimates being approximations, the board 
has sought to make them sufficiently large to cover all contin¬ 
gencies, leaviug to the engineer who may have charge of the 
construction of the work a certaiu latitude, whereby such 
changes as may appear necessary, and as circumstances call 
for, can be made as the work progresses. 

ESTIMATES. 

Section 2, from Morgan’s wharf to Congress street— 

Piles and planking at $6 33 per running foot.. $47,475 
Filling between piles, 6600 cords, at $2 50 per 

cord. 16,500 

Brush matting, 7500 feet long, 200 feet wide, in 

position and ballasted. 146,025 

$210,000 

Contingencies. 25,000 

-$235,000 

Section 1, at Carrollton— 

Brush matting, 9200 feet long, 200 feet wide, 
sunk and ballasted, at $19 50 per running 
foot.$179,600 

Contingencies. 18,600 

- 198,000 










14 


Section 3, Nine-mile Point— 

Brush matting, 2000 feet long, 200 feet wide, 
sunk and ballasted, at $19 50 per running 

foot. $29,000 

Contingencies. 4,000 

- 43,000 

Total estimated cost.$476,000 

Herewith are transmitted the drawings pertaining to the 
survey, consisting of— 

Pour index charts. 

One sketch map, showing locations of.proposed improvements. 

Two sectional drawings, showing details of proposed con¬ 
structions. 

Forty-three sheets of drawings, showing details of survey. 

There are also transmitted all the papers alluded to in our 
preliminary report, consisting of letters, views, etc., of profes¬ 
sional and other persons, in regard to the work. 

The board desire to express their acknowledgement of the 
valuable services rendered by Commodore C. P. Patterson, chief 
of U. S. Coast Survey; the officers and crews of the United 
States men-of-war Enterprise and Canonicus; Messrs. H. C. 
Collins, W. H. Williams, Geo. d’Hemecourt, M. W. Darton, H. 
S. Douglas, Eugene Thompson and Capt. M. W. Francis and 
their assistants. 

We would respectfully recommend to your Honor that provi¬ 
sion be made for completing the maps, etc., of the survey, and 
the careful preservation of same as a valuable contribution to 
the hydrography of the river in the vicinity of New Orleans. 

All of which is respectfully submitted. 

G. Weitzel, 

W. H. H. Benyaurd, 

C. W. Howell, 

B. M. Harrod, 

J. A. d’Hemecourt. 

Robert C. Wood, Secretary. 

On April 9th, the Board, after having arranged for the com¬ 
pletion of maps and publication of the report, adjourned sine 
dxe» 

Rob’t C. Wood, 

Secretary . 


/ 







15 


APPENDIX 

The following are the four interrogatories submitted by the 
Board of Engineers to those who were invited to present their 
views. 

1st. What is your opinion as to the cause of caving of the 
river bank and destruction of wharves at various points along 
the river front! 

2d. What have you observed as to effects of caving and of 
the phenomena attending? 

3d. What would you suggest as a temporary and cheap 
method of preventing caving or retarding it? 

4th. What would you suggest as a permanent measure ? 

In response to the above the following communications were 
received: 

[WM. H. WILLIAMS.] 

New Orleans, La., 
Seventh District, late Carrollton, 
Nov. 20, 1877. 

To Messrs. Weitzel, Benyaurd and Howell, 

U. S. Engineers , etc: 

Gentlemen —In compliance with your request, I offer you the 
following answers to the several questions you have submitted : 

Question 1st. As to the cause of caving in the Mississippi 
River banks and the destruction of the wharves in front of the 
City. 

Answer. My opinion is that caves are caused by the satura¬ 
tion and washing out of beds of quicksand lying at a depth 
under the banks. 

The alluvial regions, I think, are underlaid by such beds,— 
lying not in continuous strata, but rather in the form of fields 
and veins. These extend out in localities to the bed of the river, 
and by the action of violent currents, are washed into and in 
time washed out , a cavity being thus formed, iuto which the 
bank above falls. 

The first fall of the caving bank is mostly perpendicular; but 
this is followed by a sliding out movement, by which the falling 
ground, in immense quantities, is carried out some distance into 
the bed of the river. 

Such quicksand beds may be undisturbed for years, as no 


16 


caving takes place until they are reached by some accident in 
the movement of the undermining current. 

The undermining current is strongest in the apex of a bend of 
the river, or within some limited distance below. 

The wharves in the Second and Third Districts, being in and 
below the bend, are so situated as to be constantly exposed to 
the strong attack of the current from and around the Algiers 
point. 

The quicksand beds lie at various depths below the surface, 
from 15 feet to perhaps *the depth of the bottom of the river. 
Those which cause the greatest caves, I am inclined to think, lie 
the deepest, and those perhaps so deep that they cannot be 
reached by any piling or other work that might be constructed 
to prevent caving. 

This may be the case at the wharves in the Second and 
Third Districts. There may be undermining here at a depth 
of from 50 to 100 feet below the surface, and there is nothing 
iu the timber structure of the wharves that could prevent it. 
This would account for any perpendicular caving of the wharves, 
such as has occured from time to time. 

The mere falling in of the front timber-work of the wharves, 
or of the bulkhead jetties in the Third District, can be accounted 
for by the mere abrasion of the river bed, taking place outside 
of the works, and continuing until the hold of the piling is de¬ 
stroyed. 

Question 2d. As to the effects and phenomena of caves as 
known from my own observations. 

Answer . I have to say that my experience and work have 
been chiefly in the sections of the river from New Orleans up to 
Donaldsonville, and down to the Forts. Within that rauge, I 
have had much observation, and from this observation I make 
the following statements, though it must be said that the facts 
are all old, and the same as known to all other observers. 

Caves occur in the deep bends of the river, or within a certain 
limited distance below, and where the current strikes violently 
from the opposite point. This is the case in the Secoud and 
Third Districts and at Carrollton. 

Caves usually occur after the fall of the river and very seldom 
during high water. The lateral and perhaps the upward pres¬ 
sure of the water helps to sustain the bank. 


17 


Two caves seldom take place at the same point, within the 
same year, or within several years. This seems to be a confirma¬ 
tion of the sand-bed theory. The earth thrown down in the 
first cave would cover the entrance to the quicksand bed, and no 
further caving would take place, until this deposit is washed 
away by gradual abrasion. 

There is, in caving, what may be called deep caving and shal¬ 
low caving: deep caving, in which the fallen earth sinks en¬ 
tirely out of sight and is lost in the depth of the water; and 
shallow caving, in which the bank sinks perpendicularly for but 
a few feet and then rests, sometimes for a number of years. 

Caving often travels down stream in a series of years. Every 
bend in the river has an opposite point. This poiut often wears 
off to some extent, and the attack of the current passing around 
it, is thrown further down on the caving side. This is the case 
at Carrollton, where the opposite point has considerably worn 
off. But I believe it is no the case in the Third District, as the 
Algiers point has been kept up and not allowed to wear off. 

A cave is not a lateral breakiug and a lateral tumbling of the 
bank, but first a perpendicular fall and then a sliding out. 

Questioned. As to a “cheap temporary mode of preventing 
or retarding caving.” 

Answer. I must say that I have little confidence in the suc¬ 
cess of any attempt that can be made for the purpose. 

Mere abrasion either on the side of the bank, or even on the 
side of the bed of the river, can be prevented by revetting the 
bank, or by means of solid bulkheads set out from the bank. 
But these are no protection against undermining in the bed of 
the river, outside of the lines on which these works stand; and 
they are therefore no safeguard against caving. 

So far as the situation in the Third District is concerned, it 
may be that some works can be constructed there which will be 
useful against abrasions, though of no use against caving. But 
of this we are perhaps not sufficiently acquainted with the facts 
to have a definite opinion ; yet I venture the following thoughts. 

Much depends upon whether the difficulty in the Third Dis¬ 
trict has been caused by actual caving, or by mere abrasion. If 
a thorough investigation shows that the bulkheads have fallen 
only from abrasion on the river bed outside, it seems to me that 
the exposed banks could be protected again by rebuilding a 
close bulkhead nearer the shore. 


18 


If there has been actual caving, the situation is more difficult. 
Yet even then it still seems to me that for immediate protection, 
the close bulkhead might be built as the proper measure, if a 
foundation is found for the work to stand on. For immediate 
protection, either the bulkhead may have to be built or a new 
levee constructed. Yet the bulkhead would be of no use except 
as a temporary safeguard, and that only against abrasion of the 
bank, and not against caving. 

Question 4 th. As to “ what permanent measure I would sug¬ 
gest for preventing caving.” 

Answer. I would answer that I have no favorite plan to sug¬ 
gest, and I have little confidence in any I have heard proposed 
by others. 

The task required is to prevent the undermining currents from 
acting on the exposed veins and beds of quicksand. No revet¬ 
ment or bulkhead, or no work of any construction, either of 
wood or iron, could be of any value for this purpose, unless it 
could reach below the level of the lowest sand beds, which are 
to be guarded against; and these may be at an unlimited depth, 
even’as low down as the whole depth of the rirer. 

The magnitude of such a work, the difficulty of locating it 
effectively and the expense involved, would all be so great that 
the project, it seems to me, could only be regarded as practically 
impossible. 

If anything can be accomplished In the way of warding off 
the uuderminiug currents from the quicksand beds, I think it is 
most likely to be effected by a system of timber or iron jetties 
located in front of a caving bank, and built out as far into the 
bed of the river as they can be carried out and made to staud. 

The effect of these, in throwiug the body of the current away 
from the caving, and at the same time causing some deposit of 
sedimeut between jetty and jetty, might or might not be suffi¬ 
cient for the desired purpose. 

To be successful, the jetties forming the series, would require 
to be very numerous, standing close together, all projecting far 
into the river, and built with the greatest strength. 

If they should terminate before reaching deep water, they 
might not affect the lower currents down to the lowest sandbeds. 
And if they should stand too far apart, the effect on the one 
jetty would be lost before the current could reach the next. 


19 


Many other particulars would need to be considered, connected 
with the matters of location, materials and mode of construction; 
but these are not appropriate to the present stage of your inves¬ 
tigations. This project I mention, but without expressing con¬ 
fidence in it. 

Please excuse the length of these answers. They are longer 
than I desired, but the subject is so large that all I have said is 
but a skeleton of elementary facts and opinions and could not 
be embraced within a shorter space. 

Kespectfully submitted, 

Wm. H. Williams, 
Surveyor and Civil Engineer . 


[A. F. WB.OTNOWSKI.] 

New Orleans, La., November 21, 1877. 

Gen’l Godfrey Weitzel, 

Chairman Board of Engineer a, U. S. A, 

Sir —I have the honor to acknowledge the receipt of an invi¬ 
tation to be present at a meeting of your Board, also a letter 
propounding questions relative to matters at issue before your 
Board, and asking my answers to the same, which I append here¬ 
with. 

Question 1st . “What is your opinion as to the cause of caving 
of the river bank and destruction of wharves at various points 
along the river front V 7 

Answer. The causes of caving, in my opinion, may be enu¬ 
merated under five different headings, to-wit: 

First_By the force of the current striking upon an exposed 

point, as in a sharp bend. 

Second—By the scouring upon a shifting layer of quicksand 
and undermining the same. 

Third—By au over-amount of artificial weight, such as gather¬ 
ing of material, or the abutting of large levees upon others, 
over an unstable and permeating bank. 

Fourth—By submarine obstruction—not being apparent on 
the surface—disturbing the governing elements of the flow of 
water. 

Fifth—Continual rains making a heavy bank at low water to 
give way or “slough.” 


20 


From tbe position of the caves as appears on the City Map, I 
ascribe the present caves below the French Market to the first 
enumeration. That the contours and relative position of the 
river bank at that point is such as to receive the scouring force 
of the current, and will do so until the contour of the bank will 
elongate and appropriate itself to the volume and minimum 
force of the current. 

I am also led to believe that the said caving was somewhat 
hastened by the wharves built at those points of late years. 
That the piling for said wharves was not driven sufficiently deep 
to reach a firm bottom, and was, as it were, only driven to the 
bed of quicksand, and therefore adding weight, disturbing the 
strata and hastening the sloughing. 

Question 2 d, u W hat have you observed as to the effects of 
caving and the phenomena attending it?” 

Answer. The effect of caving is usually attended by a suc¬ 
cession of caves—that is, the first cave, no matter what are its 
proportions, is sufficient to disturb the regimen of the river, and 
so cause other caves in the immediate vicinity, aud generally 
above the original cave—for this reason, that where a cave takes 
place, the material carried into the river is deposited at the base, 
suddenly forming a barrier to the free flow of water above,— 
scours the bank and undermines it, hence the caving above. 
This may however not happen if a sudden and continued rise in 
the river takes place, such a freshet always transporting a 
supply of sediment which is deposited in such caves, strengthen¬ 
ing its walls and preventing a further sloughing. The increased 
volume of water carries or scours away the freshly deposited 
material from the bottom, leaving a free flow, aud thus relieves 
the bank above from an abnormal action. 

Question 3d. u What would you suggest as a temporary and 
cheap method of preventing caving or retarding it V’ 

Answer. As a temporary method—where a case occurs or is 
apparently threatened — I suggest the application of willow 
mattrassing as a revetment, of sufficient length to reach and 
cover the bottom of the cave, to be laid perpendicularly and 
properly ballasted. The mattrass to be laid above the cave, of 
such dimensions and shape (say twenty-five feet wide and two 
feet thick) as to render it flexible, so as to adapt itself to the 
shape of the bank, form one common mass with the bank, aud 


21 


thus break the undermining action of the water. These should 
be laid about one hundred feet apart, and say for three or four 
hundred feet along the bank. This method, I believe would be 
inexpensive and prove effectual. 

I would respectfully urge and call your attention as a part pre- 
Tentative to caving—that when new wharves are built, the piling 
should be driven as far as it will drive—reuew driving after a 
few days, with a heavier hammer, and penetrate by all possible 
means to firm strata beyond the action of the water—-and not 
until then will the wharves become firm. 

Question 4th. u What would you suggest as a permanent 
measure ? v 

Answer. As regards this question, I am at a loss to suggest a 
permanent system, without going beyond the limits of reasonable 
expenditures. The shiftless Mississippi will not permit such 
improvements as are made on rock bouud streams. I have how¬ 
ever seen a few portions of the river bank permanently protected. 
In one case, in front of the Camelia Plantation, in the Parish of 
St. John, where about 50 years ago tin* bank was loosely but 
rather evenly laid with brick, from an old kiln and sugar-house, 
mixed with stone ballast, for a distance of something like 400 
feet along its front, and to this time stands as firm as a rock. 
But to apply this method to 13 miles of city front, is questionable 
whether enough ballast could be obtained without an unwar¬ 
ranted expenditure. 

A very cheap material, and which has successfully been used, 
is the baggass, from sugar-houses. This forms a very good re¬ 
vetment when properly ballasted, but I doubt, even in this, if 
enough could be obtained. 

I am, however, a strong advocate of the willow mattrass 
method, and, I believe, by a liberal application along the princi¬ 
pal exposed points of the city front, some permanency would 
be secured to the prevention of caving. I think this system 
worth while trying, and so recommeud the same. 

I am, very respectfully, 

Your obedient servant, 

A. F. Wrotnowski, 

Civil Engineer. 


22 


[HENRY ELLERMANN] 

New Orleans, Nov. 21, 1877. 

To the Board of U. S. Engineers : 

Gentlemen —I have the honor to reply to your questions: — 

First. In my opinion the high and low water we had in 1876, 
was the cause of the caving of the river bank and destruction 
of the wharves at various points along the river front; low 
water, that year, was lower than it had been for thirty years 
previous. According to my observations it was 16 feet, 2 inches 
between high and low water. 

For thirty years previous to 1876, it was not as low by 1| to 6 
feet. 

I recollect that in 1856 there was only a half stage ot water, 
and during that year no caviug occurred anywhere in front of 
the city. In 1876, the depth of the channel, at from three to 
five hundred feet from the wharves, was probably 140 to 150 feet, 
and the deposit at high water was very heavy, and at low water 
this deposit would slide into the river, carrying the wharves with 
it. 

Second. In my opinion, if fewer piles were driven, the better 
it would be for the river bank. As I stated before the Board of 
Engineers, in my practice for the last thirty years I have been 
driving piles 15 to 43 feet into solid ground, and the consequence 
has been that when the caving occurred, and we had to wreck 
the old wharves, we found one pile in three broken off in the sur¬ 
face deposit, and the other piles were so split and bent as to be 
of no service. In my opinion, if heavy timber, say from 18 to 
24 inches square, were used, it would cause a greater caving 
than the timber now employed, but an experiment might be made 
to test it. 

Third. I would suggest, in answer to this question, crib-work 
for 300 feet or more where the worst caviugs have occurred, as an 
experiment,* and herewith enclose a plan for a cross-section of' 
crib-work, which I will be pleased to explain to the Board. 
This crib-work to be sunk in water, not deeper than eight feet 
nor less than five feet, with ballast and fascines. Probably this 
might succeed in making the levee solid. 

Fourth. It is my opinion that if the river had more outlets, 


* The plan is omitted. 



23 


such as exists at Bonnet Carre, it would be better for the river 
banks in front of the city, and I believe that if crevasses had 
not occurred at Morgauza and Bonnet Carre, the Third District 
would have been inundated by a crevasse there. 

In conclusion, I will remark that where the caving or land¬ 
slides in the Third District have been so great, I suggested to 
the City Surveyor to build new wharves between the old ones, 
to preveut the pulling out the old piles, which weakens the 
bank, and I will instance that at the lower end of the Liverpool 
wharf, where hundreds of old piles are to be pulled out, no 
wharf building should be done this year. 

I have the honor to be 

Very respectfully yours, 

Henry Ellermann. 


[J. HENRY BEHAN.] 

New Orleans, La., Nov. 21, 1877. 

To Genl. Weitzel, &c. 

Gentlemen of the Hydrographic Commission: 

Sirs —In answer to your interrogatories, I respectfully submit 
the following: 

1st and 2d. The caving banks in the 2d and 3d Districts, 
which are the principal points iuvolved in this issue, is caused 
by the action of the river current undermining the annual 
deposit. This deposit, composed of sand, particles of gravel 
and vegetable matter, with the immense quantity of ballast and 
debris thrown upon it from the shipping and shore, is held up 
during high water; when the river commences to fall, the 
water runs through it like a sieve until it becomes apparently 
firm, but during this process of transpiration the river has 
fallen from 8 to 12 feet, and has by the action of the current 
and the swell caused by passing steamers, also the swell caused 
by easterly winds in August and September (these winds pre¬ 
vailing at this time of low water) been undermined, and when 
the wharves become free of shipping the whole mass is precipi¬ 
tated into the river from the inside. This mass becomes dis¬ 
turbed and scattered by the current before it reaches the outer 
piling, and leaves them standing, with only a slight iucliue 
towards the river; the current by its contact with the point on 



i 


24 


tbe opposite shore is accelerated and thrown upon this bend 
with additional force, which makes it very effectual in its work 
of destruction. The effect of this caving, as has no doubt been 
observed by your Honorable Commission in your recent inspec¬ 
tion, is threatening this District (3d) at high water, with possi¬ 
bly a crevasse and inundation. 

3d and 4th. The nature of the bank along these Districts, 
from a recent inspection made by myself, have sufficient slope 
to admit of some practicable plan of permanent protection. Any 
temporary work done has to be renewed from year to year, and 
instead of being cheap, costs a vast deal more than any perma¬ 
nent work costing originally twice or even four times as much ; 
therefore, I could not, in justice to this community, suggest 
any temporary plan to your honorable body. 

The work being done by the wharf contractors is temporary 
enough and cheap enough for them, but not for the requirements 
of commerce or to the satisfaction of this community, who have 
to pay for it. 

As for a permanent work I have already submitted to you for 
your examination, accompanied with a drawiug, a plan proposed 
by myself for protecting this particular location (2d and 3d 
Districts). There seems to be some fear or antipathy to piling. 
Why *? Because it has always been done in straight lines, follow¬ 
ing the natural course of the river bank, or by bulkheads two 
or three hundred feet apart, which have been undermined by 
the current, while I propose to make the line diagonal, each 
intersection at obtuse angles, deflecting the current, causing a 
deposit instead of a wash, thereby adding strength to the work 
instead of weakening it. 

I will add that I am confident from my observations that 
a work of this nature can be made permanent to protect the 
river front, with the additional advantage of being able to have, 
in conjunction with it, permanent and sufficient wharves for the 
shipping. 

Any system of sinking mattresses on a shelving bank, without 
something to hold them, as designed in my plau, (or some other) 
will meet with the same fate as the deposit and ballast alluded 
to before, carrying with it the wharves and improvements every 


25 


year, aud finally the street and property adjoining. If a levee 
should be built to protect the street, the mattresses aud wharves 
would have to be reuewed annually, a never-ending, intermin¬ 
able and expensive job. 

Thanking you for your kind consideration, 

1 am, gentleman, 

Your very obedient servant, 

J. Henry Behan. 


[JAS. B. EADS.) 

Port Eads, November 20, 1877. 
Mr. Paul A. d’Hemecourt, Secretary. 

Dear Sir —Your letter containing certain questions addressed 
to me by the Board ol Engineers, now sitting in New Orleans, 
has been forwarded by telegraph from my office in that city. 

I have the honor to submit the following answers:— 

Question 1st . “ What is your opinion as to the cause of the 

caving of the river banks and destruction of w T harves at various 
points along the river frontf’ 

Answer. I am unable to specify the immediate or local cause 
of the caving, as your question is accompanied with no infor¬ 
mation upon the subject. 

I have not seen a survey of the river in front of New Orleans 
within the last two years, and have never examined one with 
reference to this question. 

Caving bauks on alluvial streams are chiefly caused by irregu¬ 
larities in the width of the river; these create different rates of 
current, and consequently induce scour and deposit in the neigh¬ 
borhood where these irregularities exist. When the river is tor¬ 
tuous, a slight caving in the bends will occur from the differ¬ 
ence between the velocity of the water moviug in them, aud that 
moving around the points; but the destruction of the bauks in 
the bends is so gradual, it the river above be approximately 
uniform in width, that the caving is scarcely noticeable. The 
deposit in the opposite points is likewise very slow for the same 
reason. 

Question 2d. “ What have you observed as to the effects of 
caving and of the phenomena attending itP ? 



26 


Answer. Destructive caving almost invariably occurs at, or 
immediately below a narrow part of the river, if the river be 
considerably wider above such narrow part. 

In the wide part deposition will occur so long as a lower rate 
of curreut exists there. By the loss of deposit at the wide place, 
the water is in condition to recover from the bed below the 
quantity lost above, so soon as the velocity is again increased. 

The greater value of the river front where cities are built, 
naturally stimulates the use of artificial means to protect the 
banks, and to encourage their encroachment upon the channel. 

The moving of vessels and building of wharves facilitates the 
process. Much of the refuse matter from cities, and that thrown 
overboard from vessels, is less easily removed by the current 
than the river alluvions, and the extension of the bank in such 
case is more permanent. If the opposite bank be suitably 
treated, even to a limited degree, an artificial contraction of the 
width of the stream may be created at a locality where the nor¬ 
mal width is quite uniform. In such event I would expect to 
find the current more sluggish above the contraction and con¬ 
siderable deposition occurring there; while in the contracted 
portions I would expect to find the channel deepening, and that 
this deepening would extend some distance below the contrac¬ 
tion, for the momentum due to the accelerated velocity would 
cause the rapid current to be maintained for some considerable 
distance below it. 

If the river were straight in, and for some distauce below the 
contracted part, a deepening sufficient to restore the equilibrium 
between the scouring and depositing action of the river would 
probably occur without causing a caving of the banks, as the 
material removed would be taken up mainly from the middle of 
the channel, and a considerable deepening could occur without 
disturbing the angle of rest of the banks. But if a bend existed 
below the contraction, the caving of the banks in it would occur 
from a much less amount of erosion ; and as soon as the scour 
had steepened the shore to a greater slope than the angle of rest, 
and the river had fallen, the caviug would begin. 

The angle of rest varies with the character of the deposit 
of which the banks are formed, being lowest where the deposit 
is of sand, and steepest where it is of clay. The angle of 
rest also changes with the submergence of the banks by the 


27 


rising of the river; for this reason the caving most usually occurs 
when the river is falling, for the supporting pressure of the 
water is then withdrawn from them. Hence the visible effect of 
the erosion may be delayed for months after the scour has ceased. 
So long, however, as the cause exists the scour will be repeated, 
and the caving will follow. 

I do not presume to assert positively that the caving at New 
Orleans is caused by such artificial contraction of the river as 
I have referred to. I do not even know that such contraction 
exists; I have only suggested it for the purpose of respectfully 
calling the attention of the Board to the possibility of its being 
the cause. 

Question 3 d. “What would you suggest as a temporary and 
cheap method for preventing caving or retarding it?” 

Question 4 th. “What would you suggest as a permanent 
measure V 1 

Answer . If this general explanation of the phenomena of 
caving be correct, there are evidently but two remedies, either 
of which measures will be permanent, if properly applied. The 
first is to remove the cause, which is the unequal width of the 
stream ; the second and more economic one, is to protect the 
banks from the scouring effects of the rapid current, by covering 
them with some material that will preveut any further erosion. 

The Board will appreciate the embarrassment under which I 
am responding to its interrogations, when I repeat the fact that 
I am absolutely without any data whatever upon the subject; 
nor is it likely that I can procure any before its adjournment, 
owing to the irregularities of the mails here. 

It is only through deference to the Board and a desire to pro¬ 
mote the interests of New Orleans, that I am induced to reply to 
its questions, even thus briefly, without being furnished with 
copies of such surveys of the river as are necessary to give me 
an idea of the form of its bed and banks at, aud for some dis¬ 
tance above the locality in question, together with the direction 
of its surface and sub-currents. 

No answer other than the general one I have made, can there¬ 
fore be given to the third aud fourth questions, until after such 
information shall have been supplied. 

I have the honor to be, very respectfully, 

Your obedient servant, 

Jas. B. Eads. 


28 


[ALBERT G. BLANCHARD.] 

New Orleans, La,, Nov. 21, 1871. 

To the Commission of TJ. S. Engineers : 

Gentlemen —I have the honor to submit a few concise notes in 
answer to the four questions submitted to me. 

Question 1. As to the cause of the caving of the river bank 
and the destruction of the wharves along the City front. 

Answer . By reference to my map of the section of the Arte¬ 
sian Well dug in Canal Street in 1854, the data of which are 
taken from Humphrey’s and Abbott’s Report of the Delta Survey, 
it will be seen that below the vegetable surface stratum of 2 
feet thickness, there is a stratum of Blue Clay, 14 feet thick. 

On this stratum of Blue Clay all the buildings, levees, etc., on 
the banks of the Mississippi River have their foundations. 
Below this stratum are many narrow strata of sand, or sand 
and clay or shells, down to the depth of 112 feet where a stratum 
of Dark Drab Clay is reached having a thickness of 34 feet; 
then below this Dark Drab Clay, tor a depth of 53 feet, is found 
a series of narrow strata of sand or sand mixed with clay, and 
all the sandy strata are more or less in a liquid state. This 
brings us to a depth of 196 feet, which is about the lowest depth 
of the river at New Orleans. 

The current of this vast river striking in the bends, on this 
mass of sand, washes it out from under the clay strata (some¬ 
times to a great distance, acres deep) until the weight of the 
lower clay stratum is too great to support itself, and a portion 
breaks oft and subsides towards the bottom; then the upper 
strata sink, and it is well known that acres in depth of land are 
sometimes sunk, and in high water a crevasse follows. 

Question 2. Is answered above. 

Question 3. What would you suggest as a temporary and 
cheap method for preventing caving or retarding it? 

Answer. No temporary or cheap method will answer for a 
contest with this great river, with its depth of 180 feet or more. 
Cheap and also expensive methods of preventing or retarding 
the caving of the bank have all failed, because we have only 
worked at the surface. 

We must go down to the bottom of the shelving bank, and 
face it with such a revetment as will prevent the wash of the 
current, and yet allow it to move along in its natural course; 


29 


any disturbance of the line of tbe current will only produce- 
eddies or throw it across the river, and cause caving at another 
point. 

Professor Forshey and I have estimated that a revetment of 
willow mattresses, 150 feet long, well fastened to the bank 
above high water, aud kept down by the pressure of the current 
and covered with galvanized wire netting could be laid down 
for $100,000 per mile. But as this estimate may be too low, (as 
it will require 200 feet width of mattress,) I prefer to estimate 
the cost of willow mattresses, covered with rip-rap stone, or 
galvanized wire at $50 per front foot, or in round numbers 
$260,000 per mile, which is hardly the amount sometimes 
needed to repair the damages to the wharves and levees caused 
by the caving bank of the river Mississippi, aud which is liable 
to occur every year. 

I am not fixed as to what material to use. Anything that 
will lay steadily against the bank with a uniform surface, so 
that the current will not be violently disturbed, will answer. 
Mattresses will break the current enough to cause a sediment 
between their interstices, aud so will rip raps, and thus fill up 
any inequalities of surface below them. 

Question 4. Is answered above. 

In conclusion. I beg to say to you, and through you to the 
City of New Orleans and the borderers of the river, that it will 
cost more to omit this work , than to carry it out , even at $500,000 
a mile . 

The river threatens the City with destruction, above at Car¬ 
rollton, and below in the 2d aud 3d Districts. 

Let us take warning. 

Respectfully, 

Albert G. Blanchard, 
Civil Engineer . 


[J. A. d’HEMECOERT.] 

(L. H. PILIE.] 

[L. J. FREMAUX.] 

New Orleans, November 21, 1877. 

We herewith transmit our views upon a system of protection 
of the river bank along the port of New Orleans, left bank, 
against caves or landslides occurring every year at different 
points. 



30 


The length of the port of New Orleans is simply enormous ; 
it extends from the upper limit of Carrollton to the upper limit 
of the Crescent City Live Stock Landing and Slaughter House 
Co.’s property, a distance of nearly thirteen miles. The nature 
of the banks of the Mississippi river along this line can properly 
be classed under three different heads, viz: Caving, Washing 
and Batture Banks. Under these three headings the river front 
of New Oileans is divided into six sections, as follows : 

1st. Caving bank from the upper limit of Carrollton to the 
lower end of Greenville, about two miles in length. 

2d. Batture bank from the lower end of Greenville to near 
Toledano street, about two and a half miles in length. 

3d. From Toledano to Celeste streets, about one mile and a 
half in length, the bank is generally known as a washing bank, 
although in this space several caves have occurred almost every 
year, but are restricted to ouly a few points, such as Ninth, 
Sorapuru, Market, and St. Andrew Streets. 

4th. Batture bank, from Celeste street to the Morgan’s Lou¬ 
isiana and Texas Railroad Landing, about two miles in length. 

5th. Caving bank, from Morgan’s Louisiana and Texas Rail¬ 
road to Congress street, one and three-quarter miles in length. 

6th. From Congress street to the upper limit of the Crescent 
City Live Stock Landing and Slaughter House Company’s pro¬ 
perty, about two and one-quarter miles in length, the bank may 
be termed a washing bank, although several small land slides 
have occurred opposite the Convent, at the Slaughter House, 
and a few other places. But these also are restricted to fixed 
points. 

The plan for encasing at once the Mississippi River is not a 
feasible one, and that for many reasons. 

1st. On account of its great depth. 

2d. On account of the nature of the soil through which the 
river flows in Lower Louisiana. 

3d. On account of the enormous weight of the alluvion de¬ 
posit, which would inevitably be made between the breast-work 
and the land, and which would force out the breast-work, in 
spite of all the braces that could be placed to retain it to the 
shore. 

The footing for a permanent work cannot be attained quickly, 
on account of the great depth, which in places exceeds one hun- 



31 


dred and fifty feet. To reach that great depth, we must proceed 
gradually, by lining the edge of the bank with materials that 
are not susceptible of being washed away by the under currents. 
Nothing can better serve this purpose than fascines, in connec¬ 
tion with crib-work. 

To illustrate this system, we will take for example the Sora- 
puru Cave, and describe the manner of proceeding, which would 
of course be suited to all other caves 

At the low stage of water the whole space of the cave, which 
is in shape a half circle of one hundred and fifty feet radius, 
chord three hundred feet, should be dredged to as great a depth 
as possible; this done, round piles should be planted at every 
ten feet from centre to centre, in line in each direction ; then 
mattresses, similar in construction to those used by Captain 
Eads at the South Pass Jetties, that is, composed of thin layers 
of fascines, laid at right angles to one another, should be sunk 
into the hole formed by the dredging, and should be superposed 
until the top mattresses shall have reached the height of the 
high water mark. 

As it is a known fact that piles in cavings have a tendency of 
leaning outwards, we would recommend that the piles be planted 
on an inward incline of from fifteen to twenty degrees from the 
vertical. The piling should also be made secure by means of 
crib-work, composed of round timber laid both crosswise and 
longitudinally; two pieces should be used, one on each side of 
the piles, so as to lock each pile in a square: at each intersec¬ 
tion the longitudinal pieces should be made fast to the cross 
pieces by means of rag-bolts. 

The crib-work, thus built, being perfectly independent of the 
piles, would be at liberty to slide down with the fascines, for the 
sinking of which ballast can be used. In the space between the 
high and low water marks, two rows of cribbing should be 
placed, one at about the centre, and one on top of the last course 
of matrasses. In this manner, the whole space of the cave shall 
be filled with a substance much lighter than the alluvion, and 
not susceptible of being washed away. 

This system has the double advantage of securing both a tem¬ 
porary and permanent protection. 

Temporary, in as much as it offers a quick protection; and 
permanent, because when the under current shall have under- 


32 


mined the bank at a greater depth than that reached by the 
first course of mattrasses, and the whole of the facines and crib- 
work shall have sunk out of sight, and the same process be 
applied with the exception of the dredging, and that year after 
year, until the first tier of fascines shall have reached the very 
bottom of the river, or passed the layer undermined by the 
current, the bank will present nothing but a substance that 
canuot be washed away, the protection will have become per¬ 
manent, and no more caving or landslides will occur. It will re¬ 
quire only a few years for the fascines to reach the bottom. 

This theory we have drawn from very careful observations 
made by us for the last thirty-five years, on caving banks where 
works of the nature above spoken of have been carried on, and 
which though inadequate to the present wants, have served as 
a basis for a careful study of the system that we now propose. 
These observations have been principallv carried on at a caving 
spot directly opposite the Beet Market. 

This point, situated in the middle of the bend of tne river, 
would have long ago been washed away, but for the temporary 
protection given it at high water by a treble row of ships lying 
along the wharf. Between these ships and the shore there is 
hardly any current, so that the w T ater coming there heavily 
charged with sedimentary matters, deposited a sort of artificial 
batture which was being continually undermined by the current 
of the river, at a depth greater thau that of the keels of the 
ships. Now, the water at its high stage, acted as a support to 
this overhanging batture$ but when the water receded, the 
artificial batture, having no support, went down with it, and so 
did everything to which the batture was a support, that is, 
wharves, etc. 

At this point the piles, caps, and stringers of the wharves 
were left in their sunken position, the garbage of the city and 
ballast have been thrown in the hole, new wharves have been 
built, and so on, year after year. 

In this instance the piles, stringers and caps have played the 
part of the piles and cribbing that we recommend, and the 
garbage and ballast, that of mattrasses. So perfect has this 
been that the point is solidified to such an extent that instead 
of large landslides, nothing but very slight deflections of the 
soil occasionally occur. 


33 


The wharf alluded to by Mr. Ellermann, at the foot of Hospi¬ 
tal street, has been built every year over the old piles, caps and 
stringers, for over thirty years. The wharf at that poiut is still 
sinking yearly, so that taking the slides at six feet per year, the 
first piles have reached a depth of one hundred and eighty feet. 
Between this cribbing, as formed by the caps and stringers, and 
the shore, nothing was put to prevent the undermining as was 
done in the case at the Beef Market. 

The theory of caviugs shown above, in the case of the cave at 
the Beef Market, can be applied to all caves from the Morgan’s 
Louisiana and Texas Rail Road landing to the end of the caving 
in the Third District. 

We can cite only two instances of caves occurring during the 
high water stage: one on the Lepretre Plantation, on the right 
bank of the Mississippi, about five miles below New Orleans, 
and the other also on the right bank of the river, a few miles 
above the city of Baton Rouge. 

It h as beeu observed that in the wharves, the inner piles 
settle before the outside ones, the reason of this is simple 
enough. All the battures are formed of deposits of different 
natures, usually three: coarse sand, fine sand, and light vege¬ 
table matters. The coarse sand being the heaviest is the first 
deposited, the fine sand is deposited nearer in shore, and it is 
only when the water has become motionless that the vegetable 
substances which it carries are deposited, and this is very near 
shore. This vegetable matter is compressible to a great extent, 
and is sometimes almost liquid, forming a sort of slough with 
much less consistence than the deposit formed outside. 

This last deposit offers the piles a footing much weaker than 
the deposit of coarse sand, and is the first washed away, carry¬ 
ing down necessarily the piles that are driven into it, while the 
piles driven in the coarse sand stand much longer. On account 
of the slough created between the shore and the outside deposit, 
it is not uncommon to see the inner piles lean outside, and the 
outer piles lean inside. 

J. A. d’Hemecourt, 

City Surveyor . 

Louis H. Pilie, 

Deputy City Surveyor. 

L. J. FREMAUX, 

Assistant City Surveyor . 


34 


[C. G. FORSHEY.J 

New Orleans, La., Dec. 14, 1877. 

To Genl. Weitzel and the Hydrographic Commission for the 
City of New Orleans : 

Gentlemen —Your invitation to me to join tlie engineers in 
giving opinion and experience as to the caving of the river front 
of New Orleans, reached me, in my disabled condition, after the 
adjournment of your Board. I had supposed myself omitted 
from the list of engineers addressed. 

I shall, however, add my answers to your questions as they 
occur to me, however late the communication. 

The first question is as to the cause of caving in front of the 
city. 

This question may be answered in several parts, as to the 
localities. 1 would begin below and treat the front in as- 
cending. 

1st. The left bank as far down as the Convent from Elysian 
Fields street, has been giving way from the year 1848, (?) when 
a noted cave took place carrying a number of persons with it 
most unexpectedly. The bank to the depth of 60 or 80 feet and 
200 feet -t, more than 100 feet sank suddenly down, giving 
scarce time to escape. A man on horseback disappeared and 
never was seen afterward. This was an extreme case; but it 
has been a caving or crumbliug bank ever since. This erosion 
is chiefly due to steamboat waves. The normal abrasion due to 
current and wind (very slight) teuds to encroach slowly upon 
the bank, as in all concave bends, but abnormal eucroachmeut is 
due to the accumulation of waves thrown by boats upon this 
portion of the bank. All the waves of asceuding aud descend¬ 
ing boats, rounding along the whole city front, and the ever¬ 
lasting ferry boats and running tugs, concentrate their waves— 
both direct and resultant waves—upon this cavity. If those 
banks were of stone they would wear. But formed of river 
sand, mingled with only a small portion of clay, they yield 
against the incessant forces brought against them. Here, more 
than any other along the city front, these forces are delivered. 

This concentration of forces is greatly aggravated by the 
activity of commerce, and the great docks and marine crafts 
moved along and sunk on the Algiers trout. 

2d. The special cause of the extraordinary cave iu the lower 


35 


part ot the bend is properly accounted tor by the sudden giving 
way of a sand pocket, worn into by continual abrasion. 

Many such exist, and explain much ol the river’s caving. The 
usual phenomena attending such are the sudden sinking down, 
in low water, from the great weight of the bank, unsupported 
by the wall of the water. 

3d. Ascending to the point of the upper part of the Third 
and lower half of the Second District, I would assign a totally 
different cause for the annual sinking of the bauks. This, 
too, has been long experienced, not less than twenty-five years. 
1 attribute the siuking of the banks to the exit of subterranean 
springs. These seem to have their level of discharge at no 
great depth from the surface of low water, and to discharge 
themselves with but little energy into the river at low water, 
and to discharge with them sufficient ot the stratum m which 
they live and act, to cause a subsiding of the bank above. 
They are evidently suppressed at high water by the counter 
pressure of the river water. The stratum is evidently thin and 
soft. 

There are several such places in the Mississippi river, notably 
at Brusle Landing, a few miles below Baton Rouge, Right Bank. 
The bank there, where the water rises 30 feet, subsides every 
year further back, yet never washes away till an area of near 
30 acres and more than 500 feet wide has subsided, by slices of 
ouly ten, twenty or thirty feet, and only from 6 inches to 2 feet 
at once. These springs are visible at low water and form a 
boggy margin. The like would doubtless be manifest in the 
City of New Orleans, but for the depth at which the springs 
discharge, ten, twenty or thirty feet below the low water 
surface. 

4th. The caving across the river opposite Poydras, and for 
half a mile above, I would put in the category of the Esplanade 
Convent bank, with like causes, charging to the abrasions of 
steamboat waves, from the energy with which commerce is con¬ 
ducted opposite and above. 

5th. Nothing else appears to merit special attention thence 
till we come to the Carrollton Bend. Here the City is attacked 
by the river as it is nowhere else, in the 15 miles of its front. 

6th. The Carrollton Bend may be described as reaching from 
Lowerline street in Carrollton to far above the City limits to 


36 


Camp Parapet, above tbe Preston Base of the Delta Survey. 
And the encroachment on this front may be said to be contin¬ 
ual. Its average may be measured by the removal of the levee 
of 1853, which was 174 feet for near a mile of the distance. 

This bank in the fundus of the bend, from Hoey’s brick yard 
to Cambrone street, was originally rivetted by a thick cypress 
swamp, at least from low water to ten feet above, that bound 
together by the toughness of the blue clay in which it grew, 
constituted the most nearly unyielding revetment known to the 
river, yet it has yielded to the incessant abrasion of the currents 
and waves at the rate above given. These banks, with the ex¬ 
ceptions below, are not caving banks properly speaking From 
Madison street down are crumbling banks, gradually worn away 
by the ceaseless action of currents and waves against banks of 
loamy river sand and clay, on the concave side. Towards the 
lower line, from Adams street, the current leaves the left bank 
and the crumbling is less perceptible. 

In 1853, the bank in front of and below Jefferson street, caved 
into the levee some 20 feet, aud caused the authorities to hasten 
the building of a new levee, which was retired 174 feet. This is 
believed to be the only cave proper in the past 30 years below 
the Gustine cave of 1872. 

In that year, in low water, the Augustine levee, half a mile 
above Carrollton, suddenly sank to a considerable depth, not 
less than 30 to 50 feet. The breach in the levee was 300 feet in 
length and the width of the bank that disappeared was fully 50 
feet. This subsidence was manifestly caused by the erosion 
wearing into a quick sand pocket , which at once emptied itself 
into the current of the river, and was carried away. The limit 
of this deposit was definitely found. The banks above and below 
have never given away, except to the regular abrasion of cur¬ 
rent and waves. 

The point of shore opposite has extended down stream and 
thereby increased and thrown further down in the normal 
manner the attack upon the left bank. 

Having thus examined the whole river front opposite the city, 
and answered according to the lights that many years study of 
these banks, aud the geology of their constituents, and the ob¬ 
servation of their phenomena have thrown upon them, I will 
proceed to reply to the other queries. 


37 


Question 2d. As to the effects of caving and the phenomena 
attending. 

These have been to destroy the wharves and levees and to 
render it necessary to condemn improved property for levees 
aud streets, or to destroy their value. The phenomena are de¬ 
scribed in the answer and the description of causes of the 
caving. 

Questions 3 d and 4£/i. In answer to these queries the same 
reply should be made with proper discrimination, and after a 
complete survey has exposed the shape of the bottom. No 
answer is worth much without. 

1st. In respect to erosion from natural causes aud those due 
to steamboat waves, aud those banks which have suffered from 
them, I would prescribe thus: Bevel off the front margin 
of the banks till they will bear a small pile driver 3 to 6 
feet. Then clothe the surface of the bottom at right angles 
to the bank with a netting of galvanized wire, woven in 
with cane reeds, tops down stream, beginning below and as¬ 
cending. Make the webs 10 feet ± lapping slightly, and then 
plant the piles driven home to the anchors, aud break off at the 
ground. Let this kind of work extend out to the angle of 20° 
(?) in slope of bank. 

Near shore on banks that are used for landings, use scantling 
timber of cypress or clear stuff pine and fascines for mattrasses, 
and fasten in like manner with piles. 

The only difference between “temporary” and “permanent” 
work will consist in thoroughness and weight of the material, 
and stone weights to the piles, or substitute them in quantities 
suited to necessity, on banks not too steep to hold them. This 
is my method of preventing wear from erosion. 

For the banks that sink from subterranean springs, there is 
no remedy possible where the issue of the springs are out of 
reach, as is probable in trout of the lower half of the 2d District. 
The subsidence must be looked for and preparations be made to 
fill up the sunken banks, and this should be with material the 
least abraseable, that the ordinary wear of the current shall 
carry them away the least possible. 

These banks may be covered with mattrasses as prescribed 
above. They also will be sunken by the extending stratum 
below; but structures, wharves, etc., placed in and upon them 


38 


may be raised after the subsidence has ceased, and partly be 
saved. 

An experimental bulkhead might be sunk to the greatest pos¬ 
sible depth, with the hope of cutting off the stream. They have 
a source not higher in any case than the highest ground in the 
city, and would be easily arrested if cut off. The experiment is 
worth trial, and if successful on a small scale, the bulkhead 
could be extended to the whole bank affected. 

For the caves or sudden sinking of large areas of the bank, 
like that near the Convent and at the Augustine Levee, (and, 
indeed, of frequent occurrence on the whole river front, for 
hundreds of miles above) there is possibly no remedy in human 
reach. 

If it were possible to practice a system of borings near the 
river front on all banks that are wearing, to discover the de¬ 
posits of quicksand, we might commence a system of energetic 
defence of the banks in front to stop the erosion. This will in 
a great measure be reudered unnecessary by the system of mat¬ 
tresses proposed for the banks in front of the City, that are 
gradually encroaching. 

Hitherto, no encouragement has ever been given to men of 
knowledge and science to propose expedients or remedies of 
evils that have from time immemorial menaced the City’s safety. 
In 1849-50, I made a series of 30 ± cross sections and soundings 
of the river, and again, for Capt. Humphreys in 1851, I made a 
number of sets; and again 1872-3, I repeated the same sections 
in precisely the same localities, for the purpose of comparison. 

=* * * * * * # # 
Very respectfully submitted by 

Caleb G. Forshey, 

Civil and Hydrographic Engineer . 


TELEGRAMS. 

Washington, D. C., April 3d, 1878. 
To Major Weitzel, Eugineer, 

Care of E. Pilsbury , Mayor of New Orleans, La.: 

Will you telegraph me the estimated cost of protecting the 
front of the city of New Orleans and also the necessity for it, 
and send me by mail the report of your Board on the same. 

A. A. Humphreys, 

Chief of Engineers. 




New Orleans, April 9tb, 1878. 

To General Humphreys, 

Chief Engineer , Washington : 

Estimated cost of work recommended by the Board is four 
hundred and seveuty-six thousand dollars. The necessity for 
doing it is to preserve this harbor, which in imports, domestic 
exports and foreign exports is the second in the country, and 
which is the main harbor of the Mississippi valley. The City 
is utterly unable to do the work. 

Report of Board mailed to-day. 

Weitzel, 

Engineer. 


Washington, D. C., April 8, 1878. 
To Major Weitzel, Engineer, 

Care of E. Pilshury , Mayor of New Orleans , La .: 

What is the estimated cost of the survey necessary to prepare 
a plan, and estimate of cost for the protection of the river front 
of New Orleans, against injurious encroachments of the river ? 
Answer by telegraph. 

A. A. Humphreys, 

Chief of Engineers. 


New Orleans, April 9, 1878. 

To General Humphreys, 

Chief Engineer , U. S. Army, Washington : 

The cost has been seven thousand, five hundred dollars. Less 
than one-half of the estimated cost. 

Weitzel 


VARIOUS COMMUNICATIONS. 


New Orleans, Nov. 29,1877. 

Dear Sir —On my return to-day from Port Eads, I find your 
letter of the 19th inst, awaiting my answer. 

Not having made a close examination of the river in front of 
the City, I can not suggest any definite plan for the protection 
of its bank in the 2d and 3d Districts, until accurate surveys of 
the river and observations of its current at high and low water 
shall have been made. 







40 


It is probable that the proper removal of the Point above the 
ferry landing, at Algiers, to a depth of 20 or 25 feet, would 
assist greatly in deflecting the current at high water from the 
caving banks referred to. 

I agree with the Board of Engineers in the temporary expedi¬ 
ents they recommend to the Hon. Mayor of the City in their 
preliminary report of the 24th inst. 

I remaiu, 

Yours, very truly, 

G. T. Beauregard. 

To Secretary Board of Engineers. 


IT. S. S. “-Enterprise,” * 
New Orleans, La., Dec. 10,1877. J 
Sir —1 have the honor to inform you of the arrival last night, 
at this port, of the U. S. S. “Enterprise,” under my command. 

The following extract from an order received by me from Rear 
Admiral S. D. Trenchard, commanding U. S. Naval Force on 
North Atlantic Station, explains itself. 

‘•On your arrival at New Orleans you will put yourself in com¬ 
munication with the proper authorities of the city, and offer the 
services of the vessel and the officers for the purpose of making 
a survey of the Mississippi river, at and about New Orleans, 
which it is understood the authorities are desirous of having 
made.” 

If agreeable and convenient to you, I will give myself the 
pleasure of calling at 1.30 P. M. to-day, for the purpose of 
carrying out my instructions. 

The bearer of this will await your Honor’s reply. 

Very Respectfully, 

Your obedient servant, 

Geo. C. Remey, 
Commander U. S. Navy. 

His Honor Edward Pilsbury, 

Mayor of City of New Orleans , La. 

[WM. H. WILLIAMS] 

City of New Orleans, ) 
Seventh District, late Carrollton, V 
Nov. 23, 1877. ) 

Messrs. Weitzel, Benyaurd and Howell, 

United States Engineers , etc.: 

Gentlemen —The two portions of the river front of New Or- 




41 


leans, most threatened by the caving and abrading character of 
the banks, are the Second aud Third Dsitricts, lying below 
Jackson Square, and the Seventh District, which lately tormed 
the separate City ot Carrollton, and is now annexed to New 
Orleans. 

To the Second aud Third Districts, your attention has been 
specially called, as forming the most prominent object of your 
investigation, I propose, with your consent, to ask your atten¬ 
tion, in this paper, to the condition and wants of the river banks 
in the Seventh District. 

Having been personally and officially familiar, for over twenty- 
five years, with the river and its banks and levees at Carrollton, 
it seems appropriate that I should make myself the medium ot 
conveying to you many matters of information, which you may 
be interested to learn, and which the inhabitants aud property 
owners in this neighborhood feel great interest in bringing to 
your attention, with the hope that through you, aud as a result 
of your investigations, the authorities of the United States may 
be disposed to give assistance to the work of river protection 
here required. 

The people of New Orleans and this particular District, would 
be glad to appeal to the Government for aid in doing a work 
here which is of the greatest importance to the whole City, as 
well as to the peculiar locality, but which has beeu of too great 
a magnitude to be attempted by the limited meaus of the late Cor¬ 
poration of Carrollton, and which is still too extensive to be at¬ 
tempted by the great, but greatly embarrassed City in which 
Carrollton has beeu absorbed. 

The Carrollton shore has always been subject to heavy caving 
and abrading, and is perhaps the most dangerous part of the 
river front of New Orleans. 

The brief history of the river bank here may be of some in¬ 
terest. 

The levee now standing in front of Carrollton, is the third 
general levee that has been here constructed, aud stands about 
five or six hundred feet in towards the land from what was the 
original line of water. 

The present levee was built in parts, mostly in 1853. The 
levee next preceding that was built somewhere between 1832 
aud 1835, twenty years before, and about two hundred feet 


42 


further out. Aud the levee still preceding that of 1835 stood 
probably about another two hundred feet further out, and with 
a batture of perhaps of from one to two hundred feet. Thus, the 
encroachments of the river, from caving and abrasion, amount 
within the past fifty years, to five or six hundred feet. 

The present levee, as you will perceive, if it suits your con¬ 
venience to make a personal inspection, is approached very 
closely by the river at many points. In some localities the 
bottom is very narrow; and at some points, recent caves have 
cut nearly into the crown of the levee. The necessity for a new 
levee is threatening. This would be a great misfortune. A new 
levee, now constructed here, would destroy the whole front of 
the town (or district), throwing into the river what is now the 
front or principal street, and destroying a large amount of 
private property. 

This disaster must, nevertheless, follow within a few years, 
the same to be again repeated, in all probability, after another 
twenty years, unless something can be done to put an effectual 
end to the caving aud abrasion of the bank. 

There appears to be no locality where protective measures 
against caving and abrading, if any are possible, or where any 
experimental works for that purpose could be more expedient 
or appropriate than here. As a citizen of this upper portiou of 
one consolidated city, I would not wish to divert any attention 
from the lower banks of the 2d and 3d Districts, where the 
situation and the dangers are about the same, though the en¬ 
croachments of the river have not beeu nearly so great; but 
I would like to remark that we are all now equally a part of the 
same great City, that improvement and population are traveling 
upward on the river, and that the buildiug lands of the upper 
Districts are destined to become very desirable and valuable, 
if they can be preserved for use by being protected against 
disasters from the river. 

It is presumed, of course, that the survey which you will pro¬ 
ject and recommend or execute, will include the Carrollton 
shore, aud also the shore for one or two miles above, far enough 
to embrace the conformation of bank sand currents, by which the 
Carrollton front is affected. It appears to me that both in the 
3d District, and in the 7th District, the survey of the river bot¬ 
tom should be made with peculiar detail and with the greatest 


43 


accuracy, for the reason that these are the two localities spec¬ 
ially demanding* treatment. 

For protection against caving and abrasion, there are two pro¬ 
jects or modes now engaging attention—the method of warding 
off the undermining currents of the river from the caving shore, 
by means of far-reaching jetties, and the method of revetting or 
carpeting the side of the river bottom with mattrasses. 

Neither of these could be adopted without the most careful 
and detailed survey of the river bed. If jetties should be at¬ 
tempted, they would be of little use unless they project far 
enough out to cover the outcroppings of the quick-sand beds; 
from the washing out most caving occurs. If by sounding or 
diving the position of any such outcroppings can be determined, 
this would be highly important. If mattrassing should be at¬ 
tempted, that also would be of no use, unless it should be found 
by a very detailed examination, that the surface to be covered 
is sufficiently smooth to insure that the covering would be in 
close contact with the ground. Any irregularities of surface 
that should prevent mattrassing from lying at any point close on 
the bottom, would cause under-washing, which would nullify the 
effect of the revetting, and in time might wash it entirely away. 

This minute examination of banks and bottom at particular 
points, would of course be but a part of the general survey 
that may be directed. 

This general survey, I would consider, should embrace all 
parts and sections of the river, from perhaps two miles above 
Carrollton down to the barracks, and perhaps a mile still lower 
down. It would, I suppose, include a survey of the banks on 
both sides, with the levees and battures, and a general sounding 
of the bed on cross-section lines, at suitable distances apart. 
Immediately iu the bends the cross-sections should be numerous 
and close; on the straight sections of the river, longer intervals 
would be sufficient. 

Much work of this character has been done from time to time, 
in these upper sections of the river, as well as in the portions 
in front of the old city, which is from Louisiana Avenue down 
Whenever records ot such previous works are found, it would 
seem proper that they should be made a part of the records ot 
the new survey now proposed. 

But of these general subjects, it has not been so much my 
object to speak in this communication. 


44 


In conclusion, I beg to say, that my chief purpose has been, 
and is, to invite your attention to the upper sections of the 
river, with which I have been personally familiar, as a region 
whose protection is much demanded, and where we hope the 
Government of the United States may be in some manner in 
duced, by the force of your observations, conclusions and recom¬ 
mendations, to do for our city and our people that which we 
have not the means of doing ourselves. 

As to any preference of plans or projects, I have none to ex¬ 
press. That must be left to further investigations. The subject 
is full of difficulties ; and perhaps auything now first done, may 
be but an experiment. But the necessity is so great that some¬ 
thing, it would seem, should be attempted. And if there is any 
manner in which Government aid cau be afforded, we hope that 
you, being familiar with the situation, may lend your influence 
and counsel in that direction. 

Respectfully communicated, 

Wm. H. Williams, 
Surveyor and Civil Engineer. 

To the Hydrographic Commission: 

Gentlemen —On the Algiers side of the river, opposite Mc- 
DoDoughville, while diving after old sunken material, machinery 
and boilers, I found many old wrecks, apparently one wreck 
sunk on top of another wreck, and in every conceivable posi¬ 
tion, some lying on their beam ends, and down against others 
lying more level. 

These wrecks are the accumulation of years, and form a per¬ 
fect wall, diverging the current and causing thereby an abrasion 
of the bank to such an extent, that there is now a deep channel 
between the wrecks and the bank, leaving the wrecks some dis¬ 
tance out in the river, with from 20 to 30 feet of water over 
them. There is a strong current there nearly all the time. 

Wrecks have been accumulating here since long before the 
war—steamboats of all sizes, both stern-wheel and side-wheel, to 
avoid expensive wharfage fees, were laid up abreast and some 
above McDonough vile from Algiers, and immediately above 
where the Marine Ways were sunk several years ago. 

On many occasions boats thus laid up would catch on fire, 
burn and sink; frequently when lying close together, three or 
four boats would burn at a time. 



Many of these boats before sinking would get loose, from the 
burning of their fastenings or moorings, or the pulling out of 
their stakes or posts, and there being a strong current at all 
times at this place, it would carry the boats a little down the 
river and out from the bank before going out of sight and sink¬ 
ing in deep water, where they have accumulated in like manner 
as in the place heretofore spoken of, further up the river—near 
where they were originally moored—leaving a space apparently 
of from one to two hundred feet between the irregular mass of 
wreck above and those that broke loose and sank further down. 

These boats sinking to the bottom and extending diagonally 
up, and out into the river, several hundred feet from the shore, 
form an irregular mass which, catching the current, and diverting 
it in its downward course, throws it against the bottom of the said 
bank—which is composed of soft sediment produced from the 
eddy above. 

As the bottom portion of the bank washes away, (the work of 
undermining occupies sometimes several years) the upper por¬ 
tion drops down and slides into the river, carrying everything 
with it. 

A cutting out process evidently takes place on the outside of 
the old wrecks, for whenever a slide occurs, they are moved by 
its action still further into the river—the same as the wreck of 
the Lady Franklin heretofore described. 

At this place I have sounded many times, and on many occa¬ 
sions have lost my sounding Hue, the lead having caught in the 
old wrecks. 

In 1870, I found the wrecks to be in fifty feet of water, 
whereas to-day there is seventy-five or eighty feet of water over 
them. 

The cutting out process takes place either when the river is 
rising or at high water, and the caving of the bank generally 
when the river is low or falling, aud the sliding out of the bank 
on or against the old wrecks, cause them in turn to slide into 
deep water, or into the chaunels formed by the cutting out pro¬ 
cess, the same as in the wreck of the North America. 

It is to be remarked that the cavities caused by these slides 
fill up again in a short space of time, being in the eddy. 

The steady deposit of mud upon the wreck of the Steamship 
General Grant, at high water, I account for as follows : 


46 


The Steamship lies on her beam ends quartering down the 
river, and the water below her weather side, strikes the deck 
fair, and the starboard bulwarks still remaining on, assist in 
holding the water, and in preventing the current passing over 
her weather side from below. Of course this has a tendency to 
back up the water, and, to a certain extent, momentarily con¬ 
fines it. The friction of the current outside takes away the 
water so confined, but while confined it lets fall nearly all the 
large particles of sediment of mud, tilling up from below. 

The consequence is that a continual settling and filling up of 
sediment is taking place from below, during the entire stage of 
high water. 

As the water recedes and the river becomes low, the current 
at this place changes to a variable or softening current, and at 
low water it forms a strong eddy, about on a line with the deck 
of the boat, loosening and washing away the sediment deposited 
here during the strong current in high water. 

At the wreck of the North America, the deck being parallel to 
the bank of the river, the current strikes thereon with nothiug 
to hinder its onward course, and leaves the deck clean without 
auy chance for a settlement to taks place, while at the same 
time the current driving through the hatchways, scours out the 
mud deposited during low water. 

To prevent further abrasion, and to fill up cavities where a 
strong current is washing away the bank of a bend in the river, 
commence at the head of the bend and drive down two piles of 
large dimensions, the tops if possible inclining towards the 
bank $ then bolt together a crib of timber, composed of old, but 
sound wharf timber; the crib to be from twenty-five to fifty feet 
long, and ten feet wide. 

Build the crib around the two piles, with a good, strong bot¬ 
tom, the crib to be suspended from the tops of the piles with 
ropes, and filled with ballast rock sufficient to carry it down 
and firmly hold it upon the bottom of the river. 

When ready, cut the ropes, and the crib will run down to its 
place, and beiug held in its position by the piles will there re¬ 
main until it is properly imbedded by the action of the currents. 

Other cribs should then be built at proper intervals along the 
bend, similar to the one described, save that the first crib 
should be the strongest; each crib should be about 30 feet high 


47 


in deep water, and placed iu a position to throw the water to¬ 
wards the channel of the river; the up river end of the crib 
where the current strikes it should be built flaring. 

The object is to form a wall to divert the current towards the 
channel of the river, without stopping its progress. Of course 
the current thus diverted will soon be caught by another or 
ouiter current, and carried again towards the bank where, it will 
be again resisted by another crib built lower down, and similar 
to the one first described; and so on, from crib to crib, until the 
caving bank is passed. 

These cribs may vary in height, with from 25 to 30 feet of 
water over them at low water, and are made to form a line of 
protection for the lower portion of a bluff bank. The strong 
current thus diverted wastes its streugth upon the line of crib¬ 
bing, which forms a splendid breakwater, and protects the bot¬ 
tom of the bank. 

Between the cribbing and the bauk, and below the top of the 
cribs, the slackened current lets fall all the large particles of 
sediment held in solution, which slowly fills up the cavity, and 
forms after the first year, a hard soil clay bank as high as the 
protection. 

And then where old decayed wharf timber and logs are sunk 
at the bottom, and half washed out wharf piles are still stand¬ 
ing, leaning out towards the channel of the river, catching 
stumps and debris, heretofore detrimental, will now prove useful 
in aiding to fill up and strengthen the bank, the sediment fall¬ 
ing, covering and uniting all together iu one common mass. 

Cribs could be built around wharf piles already driven with a 
beneficial effect, or wharves could be built upon the piles driven 
to support the cribbing, 

4fter the cribs are properly settled upon the bottom of the 
river, and no wharf is to be built, the tops of the piles can be 
sawed off even with the tops of the cribs, so as not to interfere 
with the shipping. 

It is at all times best to have the tops of the cribs incline to¬ 
wards the shore, to prevent scouring out from the bottom. This 
may easily be done, as the natural inclination of the strong cur¬ 
rent will be towards the bauk. 

Should it be necessary to protect the bank above the cribs, 
willow rafts or mattresses, heretofore described, may be used to 


48 


advantage. As unskilled and inexpensive labor can mostly be 
used, these cribs should only cost from fifty to one hundred dol¬ 
lars each. 

A six foot additional base, forming an inclined plane to the 
heighth of about 6 feet, might be constructed, leaving the bot¬ 
tom of the cribs flaring to receive the current and throw it in an 
upward direction, thus preventing any possibility of cutting out 
below, for at all times a current striking an inclined object lifts 
towards the surface. 

The floor beams of the cribs may be of rough logs, placed 
about 5 feet apart, with dunnage of rough material thrown 
therein, sufficient to support the stone ballast or rip-rap. 

Respectfully, 

M. W. FRANCIS, 
Submarine Diver and Contractor , 

No. 154 St. Joseph Street. 

New Orleans, March 4th, 1878. 


The charts, maps, drawings and other documents relating to 
the labors of the Board of Engineers, are on file in the office of 
the City Surveyor, New Orleans, La. 

Robt. C. Wood, Secretary. 






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